1. Field of the Invention
The present invention relates to a liquid crystal display panel. More particularly, the present invention relates to a liquid crystal display panel capable of preventing the formation of a band mura during a test period.
2. Descriptions of the Related Art
Over recent years, flat panel displays have developed rapidly and gradually replaced conventional cathode ray tube (CRT) displays. Among various flat panel displays, liquid crystal displays (LCDs) are renowned as mainstream products. As liquid crystal displays have been more widely used in automobiles and mobile products, the demands for medium- and small-sized panels grow increasingly. At the back end of the line (BEOL) during production of such medium- and small-sized LCD panels, manufacturers typically test whether the display function of the liquid crystal display panels works properly by inputting the voltage signal to the panels from a test circuit through a shorting bar. After the completion of the test at the back end of the line, the manufactures will cut off the shorting bar with a laser so that the scan lines, data lines and the test circuit are separated from each other as required for the proper operation of the liquid crystal display panels. Due to the demand of the simple manufacturing process, manufacturers now have gradually utilized thin-film transistors (TFTs) to replace the shorting bars for controlling the voltage signal from the test circuit when it has been inputted to the liquid crystal display panel.
In such conventional liquid crystal display panels, a plurality of thin-film transistors are used to electrically connect with individual scan lines, data lines and the test circuit, and works together with the test circuit to test whether the displaying function of the liquid crystal display panels works properly. When testing a liquid crystal display panel, the manufacturers turn on the thin-film transistors with the test circuit. Then, via the thin-film transistors, the voltage signal from the test circuit is inputted into the individual scan lines and data lines of the liquid crystal display panel to perform the test on the panel. After the completion of the test, the test circuit is electrically connected to a voltage supply so that the thin-film transistors will remain in the off state. In this way, by using the thin-film transistors to control the voltage signal from the test circuit when it has been inputted to the liquid crystal display panel, the back end of the line can be simplified considerably.
However, because the density and locations of the thin-film transistors in the liquid crystal display panel are not consistent across the panel, variations in the thin-film transistors may arise due to the loading effect during the manufacturing process. Consequently, when the voltage signal from the test circuit is inputted to the individual scan lines and data lines of the liquid crystal display panel via the thin-film transistors during the test, variations in electrical characteristics of the thin-film transistors, especially the greater variations in electrical characteristics between the thin-film transistors adjacent to the blank region and those far from the blank region, will cause a band mura in the liquid crystal display panel. This causes a significantly increased probability of the manufacturers misjudging such liquid crystal display panels as defective due to the band mura during the test period.
Accordingly, efforts still have to be made by the manufacturers to prevent the formation of a band mura in display regions during the test of liquid crystal display panels to decrease the probability of misjudging liquid crystal display panels as defective.